Decreasing the loss of tensile and tearing strength of cellulosic textile materials in wet processing by subjecting said materials to micro - length stretching



FIPSEOE XR n-lll-livh ii 3,533,726 Patented Oct. 13, 1970 3,533,726 DECREASING THE LOSS OF TENSILE AND TEAR- ING STRENGTH OF CELLULOSIC TEXTILE MA- TERIALS 'IN WET PROCESSING BY SUBJECT- ING SAID MATERIALS TO MICRO LENGTH STRETCHING Alfred E. Lauchenauer, Horn, Thurgau, Switzerland, assignor to Raduner & C0. A.-G., Horn, Switzerland N Drawing. Filed July 5, 1963, Ser. No. 293,128 Int. Cl. D06m 1/10, 13/70 US. Cl. 8116 14 Claims ABSTRACT OF THE DISCLOSURE The Wash and wear properties, dry and wet crease recovery, and dimensional stability of textile fabrics are improved by uniformly stretching the textile fabric in at least a slightly swollen state, at a plurality of elongation areas in a stretching zone defined by a plurality of aligned contact points lying near to infinitely near to each other, extending widthwise of the textile fabric.

The present invention relates to treating cellulosic textile material to impart finishing effects such as wash and wear properties, dry and Wet crease recovery, dimensional stability and so on, and relates particularly to improvements in treating such material by crosslinking. The main disadvantage of such processes lies in the fact that there have been high losses of the tensile strength if good effects are achieved, such losses sometimes reaching 60% or more of the original tensile strength. Losses of a similar or an even higher magnitude are observed in abrasion and tearing strengths.

Common practice in such treatment is to apply improving agents to the textile material by padding, squeeze it and dry it at least partly, and finally to crosslink, as a rule by subjecting it to a heat treatment. In other cases crosslinking is effected when the textile material still is in a swollen state, i.e. before squeezing.

It has been proposed to tension the textile material during the crosslinking step, for instance by stretching it, in the case of textile fabrics, in tenter frames, the stretching being carried out by pulling the fabric from end to end, i.e. lengthwise, or at both selvages, i.e. weftwise. Such a process is for instance described in the US. specification 2,977,665. As the figures listed there show, improvement of the tensile strength is generally speaking below Many tests carried out in textile finishing mills have shown that processes based on stretching fabrics by conventional methods in the presence of crosslinking agents, if applied in the mill, do not offer advantages which would make their application seem worth while. The reason for this is related to the fact that the conventional stretching processes consist in stretching a fabric in the direction of the filling (which usually is the weaker direction and hence would profit most from a decrease of tensile losses) by pulling it at both selvages. In such processes it is rare to produce a stretching action which is uniform over the whole length of the yarn system to be stretched due to the inevitable lack of uniformity of individual yarns (which results in a varying degree of stretching) on one hand, and due to the easily detectable differences in the degree of stretching from the selvages to the middle of the fabrics on the other hand (the degree of stretching is higher near the selvages than in the middle). Finally, it is impossible to stretch by such methods to an extent which could result in a more than marginal decrease of tensile losses.

Since the degree of stretching is extremely important for the improvement of the tensile strength, and since there is a lower limit below which no appreciable improvement at all is obtained, the only effect achieved under these conditions may be a more uniform tensile strength of the fabric components. The weaker components are stretched more and hence show less loss of tensile strength after crosslinking than .the formerly stronger parts, which are hardly affected by the stretching process and thus exhibit a normal loss of strength. This also may explain why in laboratory trials where tests are made with shorter strips of fabrics, much better results are obtained than in the mill.

With the foregoing in mind, a primary object of the present invention is to produce finishing effects based on the crossfinking of cellulose which may be obtained on textile material at least partly consisting of cellulosic fibers with substantially reduced losses of mechanical properties, particularly reduced losses of the tensile and tearing strength.

More specifically the treatment of the present invention consists of producing on such textile material, preferably when it is in an at least slightly swollen state, a rearrangement of yarns, fibers and components thereof by means of uniform stretching to at least 30%, and preferably to of the elongation at break of said textile material in the stretched direction. The stretching is carried out in small to infinitely small distance, said stretching being carried out prior to crosslinking the cellulose fibers present in said textile material.

All of the objects of the invention are more fully set forth hereinafter.

In accordance with the present invention, a substantially irreversible rearrangement of yarns and/or yarn or fiber components is produced by stretching said textile material not as usual by mechanically pulling between distant points, for instance between selvedges of a fabric, but by pulling in very small increments, i.e. by dividing the stretching area into small or even infinitely small areas, within which the stretching is uniform (microlength stretching). Such treatments producing small" increment stretching may for example consist in causing the textile material to form curves or undulations of small length perpendicular to its original surface, the original dimensions measured in that plane remaining substantially unchanged, or the stretching being carried out by pressing said textile material between two elastic bodies or one elastic and one unelastic or less elastic body such as rolls or bowls, belts or blankets, or plates in such a way that the increase of surface area produced by pressing elastic bodies against each other or against less elastic bodies causes the interposed textile material to be stretched in the desired direction or directions (one or both bodies may have surface structures causing the material to assume the undulant form), or finally by causing the textile material to be stretched by treatments between rolls, bowls or other bodies having differing surface speeds, said tex'tile material after having been stretched in the manner described in all cases being subjected to a crosslinking treatment.

The process according to the invention enables (as opposed to known processes applying tension) stretching not only in the presence of crosslinking agents, i.e. im-

mediately prior to or during crosslinking, but without any additional step during, after or prior to known treatments such' as Washing, bleaching, dyeing, caustic treatments and so on. Afterwards the textile material may be dried (keeping the dimensions obtained by stretching in the stretched direction) and then crosslinked conventionally by padding in or applying the crosslinking solution, drying (again virtually keeping the dimensions obtained by micro-length stretching) and curing. In many cases this is an advantage, since stretching during crosslinking i.e. in the presence of the crosslinking agent is known to result in a stiff and boardy hand. Micro-length stretching according to the invention may, however, also be carried out in the presence of the crosslinking agent, i.e. immediately prior to crosslinking. In every case substantially better mechanical properties, particularly better tensile and tearing strength are obtained.

The process is applicable to textile material such as yarns or fabrics consistingat least partly of cellulosic fibers. k

The elongation resulting from the mechanical treatment and the rearrangement caused thereby are irreversible in the sense that the elongation caused is not reduced by more than 50% after a standard wash at 60 if compared with the dimensions of an unstretched, similarly washed sample, and that increases of the tensile strength in the stretching direction are still noticeable after a padding/drying operation. Remaining extension means the length increase measured after removing mechanical deformations (if there are any) between marks applied prior to stretching in the stretching direction.

To carry out micro-length stretching, continuous or semi-continuous processes may be applied, making use for instance of devices described below:

Stretching in width:

Pairs of bowls or plates with surface structures arranged in a small distance from each other, running nearly parallel to the length direction, such surface structures for instance consisting in ridges alternating with grooves of the other and vice versa, for example circumferentially corrugated rolls having their corrugations meshed with one another. The depth of undulation i.e. the degree to which the fabrics are diverted from their original plane (in a right angle to that plane i.e. into the third dimension) may be used to adjust the degree of stretching. Another way of effecting micro-length stretching consist in using bowls or plates with a hard surface provided with corrugations as described above, particularly grooves running in an angle of at least 45 to the stretching direction, into which the textile material to be stretched is pressed by means of bowls, plates or belts or blankets having an elastic surface consisting of elastic material.

To effect micro-length stretching in the running direction of fabrics or yarns the same devices as mentioned above may be used, the surface structure in this case running nearly transverse to the sheet material, i.e. at an angle of 45-90 to the running direction. On the other hand devices may be used which consist of one or more bodies such as bowls, endless belts made of elastic material, which produce stretch in micro-length by making use of different surface speeds. To assure controlled microlength stretching and to avoid nonuniform stretching it is preferable to have the textile material at the places where micro-length stretching is to take place firmly held between two bodies (one of which preferably has a relatively high friction coefficient with the textile material). Finally, micro-length stretching may be achieved by pressing the textile material between two bodies, one of which has a hard, the other a relatively elastic surface. When the hard surface is pressed against the softer elastic surface, the latter surface is deformed and thereby increases in surface area. Since the elastic surface has a higher friction coeflicient with the material, the resulting surface increase causes the interposed fabric to be stretched in micro-length fashion.

If micro-length stretching is to be obtained in both directions, devices such as those mentioned above may be combined or used in succession.

In the case of woven fabrics it was found that particularly high degrees of stretching may be obtained with a higher safety margin if the direction of stretching is not fully parallel to the yarn system to be stretched, but at a small angle (usually less than 30).

The selection of the most suitable method for stretching depends in each case on the material to be stretched, the stretching direction, the effects to be obtained, etc.

Stretching may be effected at room temperature or'a elevated temperatures. The textile material may be dry or preferably at least slightly swollen, it may contain known finishing agents, dyestuffs, crosslinking agents or other finishing chemicals, particularly such which influence interfiber friction.

In many cases it was found to be advantageous to effect micro-length stretching not in one, but in several steps, i.e. to repeat the stretching treatment. Between such stretching steps the textile material may be subjected to known finishing treatments or mechanical processing.

The following indications may give some information on what stretching conditions are suitable for obtaining satisfactory effects:

The conditions applied during micro-length Stretching, which determine the degree of stretching (depth of undulation or height of deviation of alternating parts of the fabric from its original plane, and pressure if pressing between solid bodies is used as stretching means etc.) should be so adjusted to obtain an extension of the textile material in the direction to be stretched of at least 30%, preferably at least 50%, of the elongation at break, i.e. what the extension is when the same material is subjected in the same device to conditions under which it tears not only in one, but in many micro-length stretching areas. Generally speaking, it may also be said that the reduction of the extension at break (measured conventionally using strips) caused by micro-length stretching, determined by measuring the extension at break immediately prior to and immediately after micro-length stretching (without intermediate crosslinking treatment or other treatments affecting extension at break) should be at least 30%, preferably 50% or higher, if a substantial improvement of the tensile strength after crosslinking (as compared to material crosslinked conventionally in more or less slack state) is to be obtained. Another way to determine suitable minimum conditions in micro-length stretching: If a textile material is subjected to microlength stretching in wet state, the conditions as to stretching stress have to be such that the material after the treatment has a tensile strength (measured wet or after drying, without crosslinking) at least 5% higher than immediately before the treatment, determined under identical conditions.

To increase the dimensional stability of textile material treated according to the present invention, wet treatments may be carried out after crosslinking in known manner, the material may be mechanically shrunk, or crosslinking may be carried out in several steps according to the process described in US. Pat. application, Ser. No. 186,649, filed Apr. 11, 1962, now abandoned, by first pre-crosslinking under tension and then stabilizing the dimensions obtained by a second crosslinking treatment.

If the dimension increase brought about by the stretching process for some reason is undesirable, known treatments (mechanical or chemical, shrinking treatments generally speaking) resulting in a decrease of dimensions in one or both directions may be applied prior to or after micro-length stretching, i.e., one may either reduce an increase of the dimensions caused by stretching by subsequent shrinking treatments or stretch textile material which had been shrunk previously, restoring for instance by stretching the dimensions the material had prior to shrinking.

Micro-length stretching may as mentioned above be applied to yarns or textile fabrics to the full extent or incrementally at any stage of textile processing or carried out (or be completed) during the crosslinking step, i.e., it may proceed in steps, stretching not being done in one but in several steps; which if desired may be separated by a lapse of time and processing treatments. The same or different mechanical means may be used in different steps. It has for instance been found that less mechanical pull is required to obtain a given degree of elongation if the same material hadf been subjected to stretching to a similar extent at an earlier stage.

As mentioned earlier, micro-length stretching may be preferably applied to cellulosic textile material which is in an at least slightly swollen state. One may for instance subject the material to micro-length stretching after or during the usual wet treatments preceding crosslinking (bleaching, dyeing, mercerizing and so on) Without intermediate drying, i.e. in the presence of agents having a swelling actionon cellulose fibers such as for instance water, caustics, acids or salt solutions.

If micro-length stretching does not form part of the crosslinking treatment, but is applied exclusively at an earlier stage, then it is important either to avoid treatments between micro-length stretching and crosslinking which could affect the rearrangement of yarns, fibers and components =t hereof 'brought about by micro-length stretching or to repeat micro-length stretching.

At any stage, particularly immediately prior to causing the crosslinking agent to react with cellulose, the textile material may be subjected to conventional mechanical deformation such as embossing between plain or engraved 'bowls, which may be heated or cold, and the mechanical deformation may if desired be rendered fast to washing .by the crosslinking step.

The term crosslinking as it is used throughout the present application, does not only comprise the formation of covalent bonds within cellulose fibers, 'but also the formation of complexes and bonds of the character of hydrogen bonds between functional groups of adjacent macromolecular chains.

i As examples for crosslinking agents are mentioned:

Thermosetting resins of the reactant type (applied in the form of precondensates or components) obtainable from nitrogeneous compounds containing amidic nitrogen (CONH-) and monoor polyfunctional carbonyl compounds, particularly aldehydes (examples: reaction products from formaldehyde, glyoxal, acroleine and urea, cyclic alkylene ureas, ureins, triazones, or other heterocyclic compounds containing NH CO NH groups); monomeric or polymeric crosslinking agents reacting through aldehyde groups, particularly aldehydes of low molecular weight such as those mentioned above, applied in free form or as derivatives such as acetals, enol ethers, polymers, which under the crosslinking conditions used are per se capable of crosslinking cellulose or giving off compounds capable of doing so: dior polyfunctional crosslinking agents containing epoxy-, isocyanate-, vinylsulfoor other vinyl compounds capable of reacting with at least two cellulosic hydroxy groups; halogen compounds such as polyhalides, halohydrins, dicarboxylic acids in free form or in the form of derivatives; dior polyfunctional onium compounds (sulphonium, phosphonium, oxonium); reaction products of two carbonyl compounds such as ketones with aldehydes of low molecular weight (in particular oxy-methyl substituted ketones), all the compounds mentioned being brought to reaction preferably in the presence of suitable agents having a rate-increasing action (acid, basic, potentially acid or basic catalysts, radicals or radical produring compounds, radiation), and if desired also in the presence of known agents having a light to strong swelling action or influencing interfiber-friction, known finishing agents, dyestuffs, pigments.

Crosslinking reactions caused by exposing the prostretched textile material to physical/chemical influences such as heat treatments, irradiation (high energy radiation), by substitution reactions, graft polymer formation, formation of polymers in situ or deposition of polymers within the fiber, are within the scope of the present application if such crosslinking treatments per se increase the elasticity of the cellulosic fibers (in dry state) and decrease its extensibility.

If the crosslinking agent applied is a chemical compound, it may be applied as usual from solutions, dispersions or emulsions or from gas phase, crosslinking taking place after or during evaporation of volatile solvents (e.g. water), i.e. in a de-swollen or only slightly swollen state of the cellulose or in the presence of swelling agents, i.e. when the cellulose is in a swollen state. In both cases suitable catalytic agents may be used as mentioned above to increase the rate of the reaction.

As mentioned earlier, micro-length stretching may if it has not been completely carried out earlier-be effected or completed immediately prior to crosslinking. It is also possible to cause after a preliminary microlength stretching treatment only partial crosslinking, i.e. a low degree of crosslinking, and to effect further crosslinking at a later stage, for instance after the material has been subjected to further stretching.

After the cellulose has been crosslinked, stretching treatments are of no use or even harmful. On the other hand known finishing treatments such as washing, padding-on of finishing agents, softeners, pigments, compressive shrinkage treatments and of course making-up may be carried out as usual.

If particularly high creasing angles are desired or for other reasons a second crosslinking treatment may be effected after first crosslinking the stretched material under relatively mild conditions as to the concentration of the crosslinking agent and crosslinking conditions according to the sequence of steps outlined in the aforementioned U.S. application Ser. No. 186,649.

The stretching may be effected in several steps, with or without conventional finishing treatments between the several steps. Preferably the crosslinking agents are applied near the final stretching step, either immediately before or immediately after the step. The material may be mechanically deformed after the final stretching step, and the deformation may be rendered fast to washing by crosslinking.

EXAMPLES All testing results are listed in Table I. In all cases micro-length stretching resulted in an extension of more than 50% (usually 60-80%) of the extension at break. With woven cotton fabrics, the extension or elongation at break is in the neighborhood of 13%.

(1a) A cotton poplin, which had been singed, desized, bleached and mercerizled, was in wet state subjected to the following micro-length stretching treatment in weft direction (the weft yarns were weaker than the warp yarns), which resulted in a degree of stretching and hence an increase of the width of 9%: The poplin was led across curved expander rolls of the customary type to keep it wide and uncreased, and then passed between two mating metal bowls which on their surfaces had grooves alternating with ridges, the ridges of one bowl penetrating into the grooves of the other (without touching it) to a predetermined depth. The pitch of the ridges per inch was 0.177 (5.6 teeth/), the penetration was set to give a degree of stretching of 9%. After passing between the grooved bowls, the poplin had about the same width as before, but it had in warp direction grooves alternating with ridges, which when pulled out to flatten the surface gave a Width of 98 cm. The fabric was then dried to that width.

The poplin then was subjected to a crosslinking treatment by padding in a bath containing grams/liter of dimethylolpropylene urea, 14 grams/liter of zinc nitrate and 30 grams/ liter of a polyethylene softener, drying (the width of 98 cm. obtained by micro-length stretching was again maintained) and curing at 150 C. during 4 minutes.

(1b) The same poplin fabric for comparison purposes was crosslinked as. described above without previous microlength stretching, the finished width being 90 cm.

(2a) A light-weight cotton fabric (percale) was singed, desized, bleached, mercerized and dyed and then without drying subjected to micro-length stretching as described in example 1a, the degree of stretching being 11%. After drying to a width of 100.5 cm. it was crosslinked by padding in a solution of 120 g./l. formaline (36% formaldehyde by weight), 24 g./l. of a metal salt catalyst and 30 g./l. of a polyethylene softener, drying to 100 cm. width, and curing during 4 minutes at 130 C. To remove unreacted formaldehyde and the catalyst, the fabric was rinsed in slack state.

(2b) The same fabric was treated as described in Example (2a), but prior to micro-length stretching the angle between warp and filling yarns war changed to 75 by known means, the direction of stretching thus not being completely parallel to the weft yarns. The degree of stretching was 11.5% (width 100.5 cm., formerly 90 cm.). During subsequent drying the right angle between warp and filling yarns was restored. The fabric was then crosslinked as described (2a).

(2c) The fabric mentioned in Example (2a) was crosslinked as described without having been subjected to micro-length stretching.

(3a) A cotton poplin was subjected to micro-length stretching as described in Example (1a) after the usual pretreatments, the degree of stretching being 9.5% (width increase from 90 cm. to 98.5 cm.). After drying to the same width the poplin was slack mercerized (dimensions in warp direction unchanged, width decrease 8.5%, sodium hydroxide 25 B.). After neutralizing, rinsing and drying to 91 cm. the cotton was crosslinked as described in Example (1a).

(3b) The same poplin was after the pretreatments mentioned in Example (3a) subjected to micro-length stretching, drying and slack mercerization as described above, subjected to a second micro-length stretching treatment in the presence of caustic, i.e. in a highly swollen state. The width increase was 5%, which was maintained during subsequent neutralizing, rinsing, drying and crosslinking treatments (diamethylolpropylene urea as described in Example (1a)).

(3c) The same poplin was after the pretreatment slack mercerized (shrinkage 8% in weft direction), neutralized and rinsed; it was then subjected to micro-length stretching in swollen state using the method described in Example (la) (width increase 9%), dried to the maximum width obtained and crosslinked as in the preceding examples.

(3d) The same poplin after being pretreated was slack mercerized as described in Example (3c), but after being neutralized it was dried to the maximum width obtained and then padded in the crosslinking bath mentioned in Example (1a). In wet state (i.e. in the presence of the unreacted crosslinking agent) the fabric was then subjected to micro-length stretching as described in Example (1a), dried to the maximum width obtained (degree of stretching 10%) and crosslinked under the conditions given in Example (1a).

(3c) The same poplin was treated as described in Example (3c), but micro-length stretching took place prior to neutralization. The width increase obtained after flattening the fabric (pulling out the groove/ridge structure which had formed during micro-length stretching) during drying was 9%. The fabric was then dried and crosslinked as described in Example (3d) (i.e. applying a second micro-length stretching treatment in the presence of the crosslinking agent).

(3f) The poplin mentioned in Examples (3a-3d) was crosslinked as described after being pretreated without any micro-length stretching treatment (finished width 90 cm.).

(4a) A light-weight cotton fabric (cambric) after singeing, desizing, mercerizing and bleaching was padded in dry state in 140 g./l. of formaline (36% formaldehyde by weight), 24 g./l. of a metal salt catalyst and 30 g./l. of a non-ionic softener and without drying subjected to micro-length stretching in weft direction as described in Example (1a). The width increase was 10 cm. (from '90 cm. to cm.), which was virtually maintained during subsequent drying (width 100.25). Crosslinking was effected by heating to for 4 minutes. The cotton fabric then was rinsed in slack state first in an alkaline, then in a neutral bath and dried (Width 97 cm.) and subsequently compressively shrunk by mechanical means.

(4b) The same cotton fabric as in Example (4a) after having been pretreated was not subjected to micro-length stretching, but to stretching by conventional means according to US. Pat. 2,977,665, i.e. it was stretched during cross-linking by pulling at both selvages in a tenter frame. The maximum width which could be obtained without tearing off the selvages or damaging the fabric otherwise, was 95 cm. (starting width 90 cm.). The crosslinking agent and the curing temperature was exactly the same as in the process according to Example (4a). 3

(4c) The same cotton fabric was crosslinked as described in Example (4a), but without any stretching treatment (finished with 90 cm.).

(5a) A cotton fabric (percale) was subjected to micro-length stretching in weft direction as described in Example (1a) after it had been pretreated as usual. Prior to the stretching treatment 30 g./l. of a crosslinkable polyacrylate (Primal HA 8, Rohm and Haas, Philadelphia, U.S.A.) had been padded on to the fabric, i.e. stretching took place in the presence of Water and and agent increasing inter-fiber friction. Micro-length stretching resulted in a width increase after drying to the maximum width obtainable of 10 cm. (from 90 cm. to 100 cm.). The fabric was then crosslinked with g./l. dimethylolpropylene urea in the presence of 14 g./l. zinc nitrate and 30 g./l. anionic softener at C. for 4 minutes.

(5b) To the same fabric the crosslinking formulation given in Example (5a) was applied, and the fabric was then subjected to a micro-length stretching treatment in weft direction in the presence of 40% water per weight of the fabric. The width obtained and maintained during drying and curing was 98.5 cm.

(5c) The same percale was padded in the crosslinking bath mentioned in Example (5a) and then subjected not to micro-length stretching, but to stretching over the whole width during crosslinking according to US. Pat. 2,977,- 665. The maximum width obtainable without tearing off selvages was 95 cm.

(6) A cotton poplin after being pretreated as usual was subjected to a micro-length treatment as described in Example (1a). Two strands of the fabric were, however, run through the grooved rollers simultaneously one on top of the other. The production rate in the stretching step thus was doubled.

(7) The cotton poplin mentioned in Example (1a) was subjected to micro-length stretching as follows: the fabric was in wet state pressed between one grooved bowl (pitch of grooves as stated in Example (1a)) and an endless rubber belt which by tensioning was pressed against the grooved bowl and hence penetrated into its grooves. The resulting degree of stretching was 8%.

(8a) A cotton broadcloth was pretreated as usual and then subjected in wet state to micro-length stretching as described in Example (1a). The width increase was 10.5 cm. (from 84 cm. to 94.5 cm.). The fabric was then crosslinked in swollen state by padding in 120 g./L of Mykon Lubricant PB in sulfuric acid, batching, storing for 16 hours at room temperature, rinsing, neutralizing and drying.

(8b) The same fabric was treated as described in EX- ample (8a), but micro-length stretching took place only immediately after padding on the crosslinking solution. The fabric was then flattened by stretching slightly, batched, stored, neutralized and dried as in Example (8a).

(8c) The same fabric was crosslinked in swollen state 10 TN, Badische Anilin and Sodafabrik, Ludwigshafen, Germany, 140 g./l.), 12 g./l. magnesium chloride and 20 g./l. of an anionactive softener. The fabric was then in wet state subjected to micro-length stretching asdescribed in Example (la) and dried, the width thereby being increased as described in Example (8a), but without any stretching by 13.3% (from 90 cm. to 102 cm.), curing was effected treatment. at 140 for 4 minutes. The fabric then was rinsed and (9a) A cotton was pretreated as usual, then subjected dried. to micro-length stretching as described in Example (1a) (c) The same broadcloth was crosslinked with in wet state, and subsequently crosslinked in wet state Quaker Reactant 16 as described in Example (10a), but according to Example (1) of the British patent specifica- 10 without any stretching treatment. tion 894,195. Still in wet state, it was subjected to a second (11a) A cotton poplin after the usual pretreatments micro-length stretching treatment and crosslinked in dry was subjected to micro-length stretching as described in state as described in Example (1a). Example (1a) in wet state, dyed, again subjected to micro- (9b) The same poplin was crosslinked first in wet state, r gt sifetchiqg and dried agflif} to {116 maximum Width then in dry state as described in Example (9a), but withobtalned y mlcfo-length Stretchlnge out'any micro 1ength stretching I The width increased from 90 to 98 cm. The fabric (10a) A cotton broadcloth after the customary then was crosslinked by applying 140 g./l. dimethyloltreatment in Wet state was subjected to micro-length i g magneslum mtraite and of a stretching as described in Example (la) and dried (mainy fi g y to g f prevlously Obtaining the maximum width obtained). It was ten crossame an curmg or p es a linked b a l in 200 /l of an acetal of formaldeh de (11b) Same Pophn was pretreated dyed and crossy pp y g Y linked as described in Example (11a), but without any (Quaker Reactant 16) and g./l. of magnesium chloride micro length Stretching and'cunPg at 140 5 Theffilknc then was While certain examples have been set forth, it is not 1n rope form Wlthout 161151011, P softened and 5 intended to limit the invention to the treatment of woven dfabrics of this character, but other textile materials may be 10b) The same broadcloth was pretreated as usual and treated without departing fromthe scope of the invention then padded in a triazinone crosslinking agent (Fixapret as defined in the appended claims.

TABLE I Tensile Wash strength and Area Stretching (loss in Tearing Flex Creasing wear increase, Fabric Cross-linking agent treatment percent) 1 strength 2 abrasion 3 angles 4 rating 5 percent Example:

1(a). Cotton poplin 19.5(20. 5%) 250 4 7.5 1 13.5(45%) 255 4 16. 0 (22%) 250 4-5 (0) 18. 0 12%) 245 45(0. 5) 15. 5(24%) 250 4-5 (0. 5) 15 5(24%) 255 4-5 (0. 5) 0(7. 5%) 255 45(0. 5) 3(f) .dO DME U None 13. 0(36%) 230 4-5 (0. 5)

4(a) Cotton cambric Formaldehyde m.l.(f) 8. 5(35%) 280 4(0. 5) 8 4(1)) do do Accord. to U.S. 6. 0(55%) 275 4(0. 5) 4 Patent 2,977,665 7 4(0) do do None 5. 5(60%) 5(a) Cotton percalc CMPU m.l.(f) 12.0(11%) 5(b). do CMPU. m.l.(i') 9.5(%) 5(0) do CMPUMUHMQH. Accord. to US. 7.5(%)

Patent 2,977,665.

m.l. (f) 19. 0(20. 5%)

12. 0(15%) 11.5(18%) do None 9.065%) 9(a) d0 Wet crosslinkiug m.l.(f) 1s.0 27%) plus dry crosslinking. 9(b) do .do None 11. 0(55%) 10(a).. Cotton broadc1oth Acetal m.l.(f) 17. 0(20%)} 10(b o Triazinone m.l.(f) 18. 005% 10(0) Acetal None 14. 5(35%) 11(a) Poplin DMEU m.l. (f) 24. 5(9. 0%) -L 500 275 4(0. 11(b) ..d0 .d0 None 15. 5(41. 5%) 500 280 4(0. 5)

1 Tensile strength: Determined in stretched direction of course determined in the same direction in the case of unstretched samples, strips 1 wide,

4' long. Figures mean kilograms. In parentheses: loss of tensile strength in stretched direction caused by treatment.

2 Tearing strength: Elmendori Tearing Strength Tester. Values given for stretched direction only of course determined in the same direction in the case of unstretched samples.

8 Abrasion resistance: Stoll Quartermaster Abrader, flex. abrasion (load 3113s.), values given for a stretched direction only of course determined in the same direction in the case of unstretched samples.

4 Creasing angles: Sum of warp and filling creasing angles determined according to ASTMD125560 T. 5 Wash and wear rating: Determined according to AATCC Tentative Test Method 88-1961T. In parenthesis shrinkage due to washing in stretched direction of course determined in the same direction in the case of unstretched samples.

6 Area increase: Increase of area due to stretching treatment, area of unstretched sample=%. 1 USP 2,977,665: Process for increasing dimensional stability at improved tensile strength, characterized by erosslinklng under tension, i.e. stretching in the presence of crosslinking agents, no micro-length stretching.

N 0TE.-1Il.1. (f) micro-length stretching in filling direction.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for treating a woven textile fabric havin; 1111 yarns at least partly consisting of cellulosic fibers which comprises subjecting said fabric, to micro-length stretching by mechanically stretching said fabric in adjaoent small to infinitely small areas incrementally by exerting mechanical pull in the weft direction between points which are at a small to infinitely small distance from each other and define each of said small areas to elect in the stretched areas a substantially uniform stretching of the fabric to at least 30 percent of the elongation at break in the stretched direction, said textile fabric during said stretching being in atleast a slightly swollen state resulting from theaction of a liquid swelling apent.

3. The process according to claim 1 in which said fabric in said stretched areas is stretched to at least about 50 percent of the elongation at break.

3. The process according to claim 1 in which said stretching is elfected at room temperature.

4. The process according to claim 1 in which said stretching is effected at elevated temperatures.

5. The process according to claim 1 in which the uniform stretching is effected by deflecting said fabric in said stretched areas from a substantially single plane into an undulating form.

6. The product produced according to the process of claim 1.

'7. In a process for modifying a textile fabric comprisin! 1111 yarns at least partly consisting of cellulosic fibers with a cross-linking agent, the improvement which comprises subjecting said fabric prior to cross-linking to micro-lengthstretching by mechanically stretching said fabric in adjacent small to infinitely small areas incrementally by exerting mechanical pull in the weft direction m points which are at a small to annoy snail d sta ce rom one: and de ine each of smut areas to effect in the stretched areas a substantially uni form stretching of the fabric to at least 30 percent of the elongation at break in the stretched direction, said textile fabric during said stretching being in at least a swaths sta ic rcsiilti'rig from the action of a Sushi: e ling 8. The process according to claim 7 in which said fabric in said stretched areas is stretched to at least about 50 percent of the elongation at break.

9. The process according to claim 7 in which a crosslinking agent for cellulosic hydroxyl groups is applied to said fabric prior to said stretching, and said fabric is subjected to conditions which effect cross-linking by said agent subsequent to said stretching.

10. The process according to claim 9 in which a crosslinking agent for cellulosic hydroxyl groups is applied to said fabric subsequent to said stretching, and the dimensions of said fabric resulting from said stretching are substantially maintained while said fabric is subjected to conditions which effect cross-linking by said agent.

11. The process according to claim 7 in which said stretching *is effected at room temperature.

12. The process according to claim 7 in which said stretching is effected at elevated temperatures.

13. The process according to claim 7 in which the uniform stretching is effected by deflecting said fabric in said stretched areas from a substantially singleplane. into an undulating form. 1,

14. The product produced according to the process of claim 7.

References Cited UNITED STATES PATENTS 2,205,120 6/1940 Heberlcin 8--1 16.4 2,977,665 4/ 1961 McElrath 8--116.3 X 2,171,551 9/1939 Han'nig 26-63 FOREIGN PATENTS 424 2/1866 Greatllritain. 14,608 *ll/ 1884 Great Britain.

1,895 4/1895 Great Britain. s,23 o 311901 Great Britain. 486,925 6/1938 Gl'cat, Bi'italn. 550,493 1/1943 Great Britain.

J. CANNON, Assistant Examiner U.S. Cl. X.R. 8- 541, 107, 115.7, 116.2, 116.3, 116.4, 120,

LESMES. irimcry Examiner all 

